O fenômeno qualidade de vida (QV) vem sendo amplamente estudado em ensaios clínicos e pesquisas científicas de doenças crônico-degenerativas e demências. Não há ainda disponível, em nossa cultura, um instrumento confiável e válido para avaliar QV nos quadros demenciais e, especificamente, na doença de Alzheimer (DA). O presente estudo tem por objetivos: avaliar as propriedades de medida da versão em Português da escala \"Quality of Life-AD (QOL-AD)\", avaliando a confiabilidade e a validade de constructo das três versões (PQdV, C-PQdV e CQdV) e também o impacto do comprometimento cognitivo sobre as propriedades de medida. A escala QOL-AD foi desenvolvida por Logsdon et al. em 1999. O instrumento é composto de 13 itens quantificados em uma escala de quatro pontos, sendo a pontuação 1 atribuída à qualificação ruim e a pontuação 4, à excelente. A pontuação total varia de 13 a 52, em que os índices mais altos indicam melhor QV. A escala possui três versões de avaliação de QV: o relato do paciente sobre sua QV (PQdV), o relato do cuidador/familiar sobre a QV do paciente (C-PQdV) e a versão do cuidador/familiar sobre sua própria QV (CQdV). A escala foi administrada a uma amostra de 60 pacientes com diagnóstico de DA provável, segundo os critérios do NINCDS-ADRDA, sendo 30 pacientes com grau leve e 30 pacientes com grau moderado de demência, segundo os critérios do DSM-III-R, e a seus respectivos cuidadores/familiares (n=60). A confiabilidade da escala foi avaliada através do alfa de Cronbach. Para a verificação da validade de constructo, as três versões da escala foram associadas às avaliações do funcionamento cognitivo, desempenho funcional, alterações de comportamento, sintomas depressivos e de nível socioeconômico e ao instrumento genérico de avaliação de QV (WHOQOL-breve). A confiabilidade da escala foi elevada, tanto para a versão do PQdV, como para a versão C-PQdV (alfa=0,80 e 0,83, respectivamente), quanto para a versão CQdV (alfa=0,86). Na validade de constructo da versão PQdV encontramos correlações significativas com: sintomas depressivos (GDS (-0,59, p<0,01) e Cornell (-0,49, p<0,01)), alterações de comportamento (-0,36, p<0,01) , com a questão número 1 (0,67, p<0,01) e o somatório do WHOQOL-breve (0,88, p<0,01). Na versão C-PQdV, foram encontradas correlações significativas com: comprometimento cognitivo (0,41, p<0,01), sintomas depressivos (GDS (-0,36, p<0,01) e Cornell (-0,68, p<0,01)), desempenho funcional (AIVDs (-0,52, p<0,01) e ABVDs (-0,51, p<0,01), alterações de comportamento (-0,71, p<0,01), com a questão número 1 (0,61, p<0,01) e o somatório do WHOQOL-breve (0,71, p<0,01). Na versão CQdV, as correlações encontradas foram com sintomas depressivos (Cornell (-0,30, p<0,05) e Inventário de depressão de Beck (-0,59 p<0,01)), alterações de comportamento (-0,39, p<0,01), desempenho funcional (AIVDs (-0,41, p<0,01) e ABVDs (-0,32, p<0,01),com a questão número 1 (0,55, p<0,01) e o somatório do WHOQOL-breve (0,81 p<0,01). A confiabilidade e a validade de constructo da escala foram mantidas independentemente do aumento da gravidade da doença. O gasto médio na aplicação da escala foi de aproximadamente seis minutos para cada uma das três versões. Os resultados indicam a confiabilidade e a validade constructo da versão em Português da escala de avaliação de QV na população estudada / The concept quality of life (QOL) has been extensively studied in clinical trials and in research of chronic-degenerative diseases and dementia. We do not have in our culture instruments available to evaluate QOL in dementia and, particularly, in Alzheimer\'s disease (AD). This study has the following objectives: to evaluate the psychometric properties of the Portuguese version of the scale, evaluating the reliability and construct validity of the three versions (PQdV, C-PQdV e CQdV), and the evaluation of the impact of cognitive performance on the psychometric properties. The scale \"Quality of Life-AD (QOL-AD)\" was developed by Logsdon et al. in 1999. The instrument is composed of 13 items quantified in a scale of four points, with the score 1 being attributed to the qualification poor and the score 4, to excellent. The total score varies from 13 to 52, with the highest indexes indicating better QOL. The scale has three versions of QOL evaluation: the QOL indexes from the patient\'s report on his/her own QOL (PQdV), the caregivers/family report on the patient\'s QOL (C-PQdV) and the version on QOL of the caregivers/family (CQdV). The scale was administered to a sample of 60 patients with diagnosis of probable AD, according to the NINCDS-ADRDA criteria, being 30 patients with mild dementia and 30 patients with moderate dementia, according to the DSM-III-R criteria, respectively, and to their caregivers/family members (n=60). The scale reliability was evaluated through Alfa\'s Cronbach. The construct validation was accomplished based on the correlations of the three scale versions with cognitive evaluation, functional performance, behavior disturbances, depressive symptoms and socioeconomic level and with a generic instrument of QOL (WHOQOL-brief). The scale reliability was high, both for the PQdV and for the C-PQdV version (alfa=0.80 and 0.83, respectively), as much as for the CQdV version (alfa=0.86). We observed significant correlations in the construct validity of PQdV version: with depressive symptoms (GDS (-0.59, p<0.01) and Cornell (-0.49, p<0.01)), behavior disturbances (-0.36, p<0.01), with the first item (0.67, p<0.01) and with the total score of WHOQOL-brief (0.88, p<0.01). We obtained significant correlations in the construct validity of the C-PQdV version: with cognitive impairment (0.41, p<0.01), depressive symptoms (GDS (-0.36, p<0.01) and Cornell (-0.68, p<0.01)), functional performance (AIVDs (-0.52, p<0.01) ABVDs (0.51, p<0.01), behavior disturbances (-0.71, p<0.01), with the first item (0.61, p<0.01) and with the total score of WHOQOL-brief (0.71, p<0.01). In the CQdV scale, the significant correlations were related to depressive symptoms (Cornell (-0.30, p<0.05) and Beck Depression Inventory (-0.59, p<0.01), behavior disturbances (-0.39, p<0.01), functional performance (AIVDs (-0.41, p<0.01) e ABVDs (-0.32, p<0.01), with the first item (0.55, p<0.01) and the total score of WHOQOL-brief (0.81, p<0.01). The scale reliability and construct validity were kept independently from the disease level. The scale took, on average, six minutes for each of the three versions. The results indicate reliability and construct validity of the Brazilian version of QOL-AD in the sample studied

A doença de Alzheimer (AD) é a doença neurodegenerativa relacionada ao envelhecimento mais frequente no mundo. Uma das características moleculares de AD é a produção exacerbada de peptídeos beta-amiloide (A&beta;), principalmente dos fragmentos de 40 e 42 aminoácidos (A&beta;1-40 e A&beta;1-42). A&beta; induz respostas neuroinflamatórias e alterações moleculares relacionadas à perda sináptica e morte neuronal. Diversos relatos mostram que pacientes de AD apresentam redução na concentração plasmática de melatonina, hormônio produzido pela glândula pineal e também alteração na expressão dos receptores de melatonina, mas os mecanismos envolvidos ainda não são conhecidos. De acordo com o conceito do eixo imunepineal, agentes inflamatórios são capazes de atuar diretamente sobre a glândula pineal e inibir a síntese de melatonina. No presente estudo investigamos, portanto, se o peptídeo A&beta; atua diretamente sobre o sistema melatonérgico, modulando a síntese de melatonina ou a função de seus receptores. Pineais em cultura tratadas com A&beta; 1-40 ou A&beta; 1-42 apresentaram redução na produção de melatonina. A&beta; 1-40 ativou a via do fator de transcrição NF-&kappa;B na pineal, resultando em aumento da transcrição de diversos genes inflamatórios, como interleucinas e quimiocinas, e inibição da expressão da enzima arilalquilamina N-acetiltransferase, essencial à síntese de melatonina. Em células HEK293 expressando estavelmente receptores MT1 ou MT2 recombinantes, a ativação da via ERK1/2 pela melatonina foi inibida tanto por A&beta; 1-40 quanto por A&beta; 1-42. O mesmo efeito inibitório foi observado em células endoteliais primárias que expressam MT1 e MT2 constitutivamente. O presente trabalho mostra que a síntese de melatonina pela pineal e a função dos receptores de melatonina são diretamente regulados por A&beta;, o que amplia nossos conhecimentos a respeito dos efeitos prejudiciais de A&beta;. Considerando que a melatonina tem propriedades neuroprotetora e antioxidante, a disfunção do sistema melatonérgico pode contribuir para os processos neurodegenerativos que ocorrem na patologia de AD / Alzheimer\'s disease (AD) is the most common age-related neurodegenerative disorder worldwide. Excess of amyloid beta peptides (A&beta;), composed mainly by 40 and 42 aminoacids-long fragments (A&beta; 1-40 e A&beta; 1-42) is a molecular hallmark in AD. A&beta;-induced neuroinflammatory responses and molecular changes are related to synapse impairment and neuronal loss. It is well documented that AD patients show impaired melatonin synthesis, the pineal gland-derived hormone, and altered expression of melatonin receptors, but the underlying mechanisms remain unclear. According to the immune-pineal axis concept, inflammatory mediators act on the pineal gland, leading to inhibition of melatonin synthesis. Therefore, in the present study we sought to investigate whether A&beta;? directly targets the melatonergic system, modulating melatonin synthesis and/or melatonin receptors function. Pineal glands cultured in the presence of A&beta; 1-40 or A&beta; 1-42 showed reduced melatonin production. A&beta; 1-40 activated the nuclear factor kappa B (NF-&kappa; B) pathway in the pineal gland, leading to up-regulation of several inflammatory genes, as interleukins and chemokines, and inhibition of the arylalkylamine N-acetyltransferase enzyme expression, the key enzyme in melatonin synthesis. In HEK293 cells stably expressing recombinant melatonin MT1 or MT2 receptors melatonin-induced ERK1/2 activation was markedly impaired by A&beta; 1-40 and A&beta; 1-42. Similar results were obtained in primary culture of endothelial cells expressing melatonin receptors endogenously. The present study shows that melatonin synthesis and melatonin receptors function are directly impaired by A&beta;, thus extending our understanding on the detrimental effects of A&beta;. Because melatonin shows neuroprotective and antioxidant properties, impairment of the melatonergic system may contribute to the neurodegenerative processes that take place in AD. 1-42) is a molecular hallmark in AD. A&beta;-induced neuroinflammatory responses and molecular changes are related to synapse impairment and neuronal loss. It is well documented that AD patients show impaired melatonin synthesis, the pineal gland-derived hormone, and altered expression of melatonin receptors, but the underlying mechanisms remain unclear. According to the immune-pineal axis concept, inflammatory mediators act on the pineal gland, leading to inhibition of melatonin synthesis. Therefore, in the present study we sought to investigate whether A&beta;?directly targets the melatonergic system, modulating melatonin synthesis and/or melatonin receptors function. Pineal glands cultured in the presence of A&beta; 1-40 or A&beta; 1-42 showed reduced melatonin production. A&beta; 1-40 activated the nuclear factor kappa B (NF-&kappa B) pathway in the pineal gland, leading to up-regulation of several inflammatory genes, as interleukins and chemokines, and inhibition of the arylalkylamine N-acetyltransferase enzyme expression, the key enzyme in melatonin synthesis. In HEK293 cells stably expressing recombinant melatonin MT1 or MT2 receptors melatonin-induced ERK1/2 activation was markedly impaired by A&beta; 1-40 and A&beta; 1-42. Similar results were obtained in primary culture of endothelial cells expressing melatonin receptors endogenously. The present study shows that melatonin synthesis and melatonin receptors function are directly impaired by A&beta;, thus extending our understanding on the detrimental effects of A&beta;. Because melatonin shows neuroprotective and antioxidant properties, impairment of the melatonergic system may contribute to the neurodegenerative processes that take place in AD

University of Macau / Institute of Chinese Medical Sciences

Protein aggregation, oligomer and fibril formation is one of the dominant characteristics in the pathogenesis of a number of neurodegenerative diseases, such as Alzheimer’s disease (AD). Inhibition of toxic oligomer and fibril formation is one of the approaches to find potential drug candidates for AD. Additionally, early diagnosis of these amyloid species can provide mechanistic understanding of protein aggregation and thus can pave the way for preventing the onset of AD. The aim of this dissertation was 1) to explore the effects of charged cholesterol derivatives on the aggregation kinetic behavior of Amyloid-β40 (Aβ40), 2) to probe Aβ40 oligomer and amyloid formation in vitro using gold nanoparticles (AuNPs), and 3) to monitor the kinetic effect of various natural product molecules on Aβ40 aggregation in vitro. In the first chapter, a general introduction about AD as an amyloidogenic disease, amyloid cascade hypothesis, and the manipulation of Aβ peptides aggregation kinetics using different approaches was presented. In the second chapter, we studied the effects of oppositely charged cholesterol derivatives on the aggregation kinetics of Aβ. In the third chapter, we developed a gold nanoparticles (AuNPs) assay to probe Aβ40 oligomers and amyloid formation. In chapter IV, we monitored the effects of various small molecules on the aggregation kinetics of Aβ40. In chapter V, we discussed the methods and experimental details. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Genetic factors involved in late-onset Alzheimer’s disease (AD), affecting the majority of AD patients, are largely unknown. Genome-wide association studies implicated genes associated with increased risk of AD, including BIN1 (Bridging Integrator 1), and MSRB3 (methionine sulfoxide reductase-B3), also associated with low hippocampal volume. In an effort to find effective therapies, animal studies using intracerebralventricular administration of neurotrophic factor bone morphogenetic protein-9 (BMP9) decreased pathological burden and preserved cholinergic phenotype in AD mouse model hippocampus. To examine the potential role of BIN1, MSRB3, and ALK1, the BMP9 receptor, in human hippocampal AD-associated pathology, we examined their protein expression in postmortem human hippocampi using automated immunohistochemistry, and correlated the data with neuropathological reports and clinical dementia ratings. In elderly control subjects, BIN1 protein was expressed in white matter, glia, and neuropil along axons. CA1 quantitative analysis of BIN1 signal during AD progression revealed expression decreased in neuropil and increased in the cytoplasm of pyramidal neurons. The number of CA1 BIN1-immunoreactive pyramidal neurons correlated with the hippocampal CERAD neuritic plaque score while BIN1 neuropil signal was absent at neuritic plaque sites. MSRB3 was differentially expressed in hippocampal pyramidal layers. Controls exhibited MSRB3 signal as distinct but rare (≤2) puncta in CA1 pyramidal neuron somata. MSRB3 immunoreactivity in CA3 was found in the pyramidal layer neuropil. MSRB3 signal was also observed in rodent hippocampi where ultrastructural and immunohistofluorescent analysis revealed MSRB3 associates with synaptic vesicles (SV) and colocalizes with SV and mossy fiber markers respectively. In AD patients the population of CA1 pyramidal neurons with frequent (≥5), rather than rare, MSRB3-immunoreactive somatic puncta increased in comparison to controls and correlated positively with AD pathological hallmarks. Finally, cholinergic neurons of human and rodent basal forebrain were ALK1-immunoreactive. In healthy CA1, ALK1 was expressed prominently in neuropil and in GABAergic interneurons, while CA2, CA3, and CA4 showed ALK1-immunoreactive neuropil and pyramidal somata. The intensity of ALK1-immunoreactivity in CA3 decreased in moderate and late AD patients compared to non-AD subjects. These data show that neuronal, glial, and hippocampal subfield-specific changes in protein expression of potential AD modulators are associated with AD progression and its diagnostic hallmarks. / 2020-06-12T00:00:00Z

A doença de Alzheimer (DA) é complexa e de etiologia desconhecida. Provavelmente componentes multifatoriais influenciam no desencadeamento dessa patologia, sendo que o único fator genético de risco bem estabelecido até o momento para a doença é a variante alélica APOE*E4. Nos últimos anos, descobriu-se uma série de polimorfismos em genes diferentes sugerindo que essas alterações possam ter participação discreta na patologia. O presente estudo avaliou vinte e um polimorfismos distribuídos em treze genes, sendo estes APOE, ACE, APP, BDNF, CALHM1, CST3, GAB2, GAPDH, GSK3B, GSTP1, IL1A, IL1B e SORL1 , em pacientes, controles idosos e indivíduos com comprometimento cognitivo leve, na tentativa de verificar se existe algum tipo de associação entre os polimorfismos investigados como fatores de risco para DA. Nossos resultados mostraram associações positivas entre cinco polimorfismos conferindo risco elevado para o desenvolvimento de DA (rs429358 e rs7412 de APOE, rs2373115 de GAB2, rs6438552 de GSK3B e rs641120 de SORL1). Outro achado consistente de nosso estudo foi que 20/21 polimorfismos estudados apresentaram ao menos um genótipo associado com risco elevado para DA na presença de um alelo APOE*E4. Com nosso trabalho contribuímos para aumentar o conhecimento sobre a etiologia da DA, identificando possíveis marcadores moleculares de suscetibilidadenessa patologia. / Alzheimers disease (AD) is complex, and its ethiology is not completely understood yet. It is likely that multifactorial components do account for this pathology development, being the allelic variant APOE*E4 is the only well-established genetic risk factor so far. Recently, a series of polymorphisms located at different genes were related to AD, suggesting that those variations might have a modest participation in this pathology. The present study evaluated twenty-one polymorphisms distributed in thirteen genes, being them APOE, ACE, APP, BDNF, CALHM1, CST3, GAB2, GAPDH, GSK3B, GSTP1, IL1A, IL1B and SORL1, in elderly controls, AD and mild cognitive impairment patients, attempting to verify if there is any kind of association between the selected polymorphisms as risk factors for AD. Our results show positive associations between five polymorphisms and AD (APOE rs429358 and rs7412, GAB2 rs2373115, GSK3B rs6438552 and SORL1 rs641120). Another consistent finding was that 20/21 polymorphisms analyzed showed at least one genotype associated with increased risk for AD at the presence of at least one APOE*E4 allele. We intend that our research might contribute to increase what is known about AD ethiology, by deciphering possible molecular susceptibility markers evolved with this pathology.

G-substrate is a 23 kDa protein named as a specific substrate of cGMP-dependent protein kinase and found predominantly in cerebellar Purkinje cells. As a component of the NO/cGMP/PKG pathway, G-substrate is potentially involved in several important cellular processes and has so far been associated with a number of disease conditions: a single point mutation in G-substrate has been linked to hypercholesterolaemia, while the potent inhibition of PP2A by phosphorylated Gsubstrate possibly influences Tau protein hyperphosphorylation and contributes to Alzheimer's disease pathology. Conversely, overexpression of G-substrate protein in dopaminergic neurons has been found to protect neurons from Parkinson's disease toxins, making G-substrate a possible target of interventions for mitigating the debilitating effects of Parkinson's disease on patients. A shorter splice variant, which only retains one of the phosphorylatable threonine motifs, has recently been described for G-substrate and given the importance of phosphorylation to its action as a phosphatase inhibitor, this study focuses on determining whether both variants of the protein exhibit similar levels of phosphatase inhibition and interact with the same/similar proteins in vivo. We were also interested in determining whether the 51 amino acid section absent from short G-substrate resulted in any significant differences in protein structure, which potentially has implications on functions in vivo. My results indicate the association of G-substrate with a wide range of proteins involved in processes including cell cycle regulation, endocytosis and signalling and the two variants do not always interact with the same proteins. Among these interactors is the PARK 7/ DJ-1 protease, which like G-substrate has been shown to be neuroprotective. I have found that G-substrate is proteolysed by DJ-1 in its active form and interactions between these two proteins is affected by the anti-vertigo drug Tanganil. Phosphatase inhibition studies suggest that the G-substrate variants affect phosphatase activity to different extents under similar conditions, while NMR and circular dichroism structural studies suggest that in solution, the full length Gsubstrate variant is slightly more compactly folded. Understanding the details of G-substrate action in the cell will lead to a better understanding of its roles including the protection of dopaminergic neurons from Parkinson's disease toxins and shed more light on the intricacies of the NO/cGMP/PKG signalling pathway as a whole, thus providing important information that might help improve strategies for dealing with conditions involving this pathway and help develop interventions for diseases such as Alzheimer's and Parkinson's.

Orientador: Florindo Stella / Banca: Hanna Karen Moreira Antunes / Banca: Gustavo Christofoletti / Resumo: Os objetivos deste estudo compreenderam: a) caracterizar a presença de apatia em pacientes com DA residentes na comunidade; b) analisar os efeitos do treinamento com pesos na apatia, funções cognitivas frontais, funcionalidade motora e variáveis metabólicas destes pacientes; c) verificar as possíveis relações antes e após quatro meses de treinamento com pesos, na apatia, funções cognitivas frontais, funcionalidade motora; e d) verificar se há diferenças em funções cognitivas e funcionalidade motora segundo o nível de apatia dos pacientes. Para tanto, participaram do estudo 28 pacientes com DA, com idade média de 78,8 ± 6,6 anos, escolaridade de 4,8 ± 3,5 anos que foram alocados em grupo treinamento (GT) e grupo de convívio social (GCS). Todos os pacientes foram avaliados de acordo com os seguintes testes: Escore de Avaliação Clínica de demência; Questionário Baeck Modificado para Idosos; Mini Exame do Estado Mental; Montreal Cognitive Assessment; Teste de Fluência Verbal semântica; Teste do desenho do Relógio; Bateria de Avaliação Frontal; Escala Cornell para Depressão em demência; Inventário Neuropsiquiátrico (domínio Apatia); Bateria de Testes Motores de Andreotti & Okuma; protocolo do Banco de Wells; Teste de Resistência de Membros Superior da Bateria de Testes da AAHPERD; Teste de Sentar-se e Levantar-se da cadeira em 30 segundos. Além disso, os pacientes realizaram exames laboratoriais para mensurar níveis séricos de Colesterol Total e frações, Homocisteína e Glicemia. O GT realizou um protocolo de treinamento com pesos (TP) durante quatro meses, três vezes na semana, em dias não consecutivos com duração de 60 minutos cada sessão. Este treinamento consistiu em realizar três séries de 20 repetições com intervalo de dois minutos entre séries e exercícios para os... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objectives of this study were: a) characterize the presence of apathy in community dwelling patients with AD; b) analyze the effects of resistance training on apathy, frontal cognitive functions, motor function and metabolic variables of these patients; c) verify possible relations before and after four months of resistance training in apathy, frontal cognitive functions, motor function; and d) verify if there are differences in cognitive and motor function according to the level of apathy of the patients. To do so, participated in the study 28 patients with AD, mean age 78.8 ± 6.6 years, education 4.8 ± 3.5 years who were divided into training group (TG) and group of social interaction (GSI ). All patients were evaluated according to the following tests: Clinical Dementia Rating; Modified Baecke Questionnaire for Elderly; Mini Mental State Examination; Montreal Cognitive Assessment; Semantic Verbal FluencyTest; Clock Drawing Test; Battery Frontal Assessment; Cornell Scale for Depression in dementia; Neuropsychiatric Inventory (domain Apathy); Motor Battery Test of Andreotti &Okuma; Wells protocol; upper limb strength from AAHPERD battery; Sit and Stand up from a chair in 30 seconds. Besides that, the patients undertook laboratory tests to measure serum levels of total cholesterol and fractions, homocysteine and glucose. The TG participated in a resistance training protocol (RT) for four months, three times a week on nonconsecutive days lasting 60 minutes each session. The training consisted in performing three sets of 20 repetitions, with two minutes between sets and, exercises for major muscle groups. GSI participated in reading, clippings, group dynamics activities and non-systematized mild walking during the same period, frequency and duration of the RT. It was used as statistical analysis... (Complete abstract click electronic access below) / Mestre

Down’s Syndrome (DS) is a genetic disorder associated with intellectual disability, accelerated aging and a propensity for early-onset Alzheimer’s disease (AD). Beta-amyloid plaques are one of the pathological hallmarks of AD, and also a common characteristic of the older DS brain. AD treatment trials are now moving towards administration of the intervention at preclinical stages, with the goal of preventing cognitive decline in the first place, rather than trying to halt or reverse existing pathology. Consequently, it has become essential to develop biomarkers of AD, which can: 1. Predict clinical changes and 2. Track the effectiveness of putative preventative treatments. The strong association between DS and AD means that this research is particularly important for people with DS and it presents a high-risk group for exploring predictive biomarkers. Electroencephalography (EEG) is a non-invasive and inexpensive measure of cortical activity, which is being evaluated with the typically developing (TD) population as a potential biomarker of AD. This thesis aims to evaluate EEG as a potential predictor of cognitive decline associated with DS-AD. There are several potential EEG measures that could be explored. Following a review of the literature, the predictive potential of the following event-related potentials (ERPs): mismatch negativity (MMN) and P300 (P3a and P3b), were chosen for exploration with cross-sectional and longitudinal investigations. The thesis begins by exploring how the ERPs differ for a cross-section of 36 adults with DS and 39 age- and gender-matched TD controls. As expected, the MMN waveform was smaller for adults with DS than TD controls. However, the P3b waveform was predominantly absent for adults with DS, whilst the P3a response was significantly enlarged. The P3a response was also enlarged for the adults with DS who scored lower on a neuropsychological measure. The neuropsychological measure indexes frontal functions, which are compromised early in DS-AD. This experiment also provided evidence that MMN was related to age in DS, with increasing latencies and decreasing amplitudes for older participants. The differences in MMN amplitude between the groups (DS, TD) were isolated to the older adults. These findings lend support to the premature aging hypothesis of DS. The thesis also included a longitudinal follow-up in which 34 adults with DS underwent a repeated cognitive examination one year after their EEG and initial cognitive assessment. The analyses found that adults with DS who had lower MMN amplitudes at the initial assessment were more likely to decline at the cognitive follow-up. This finding suggests that MMN may be a potentially useful clinical tool for predicting the cognitive decline associated with DS-AD.

Endosomal dysfunction has been mechanistically linked to Alzheimer’s Disease (AD). To date, no in vivo biomarkers for this cellular deficit exist. Yet such biomarkers are required for determining its prevalence in AD and tracking its time course—both in disease progression and potential clinical trials. With this goal in mind, we made use of an assortment of mouse models bearing AD-related endosomal trafficking defects through selective deletion of retomer core proteins. We collected CSF and brain exosomes from these retromer-deficient models and performed a battery of molecular inquiries which included lipidomic and proteomic screens, as well as hypothesis-driven biochemistry. The results of this comprehensive investigation include the first characterization of the murine CSF lipidome and the deepest characterization to date of the murine CSF proteome. Herein, we report that VPS26a haploinsufficiency in the brain imparts no detectable protein changes in the CSF as measured by labeled LC-MS/MS at three months of age. This deficit does, however, cause a reliable reduction of CSF sphingomyelin d18:1/18:1, which is exacerbated by age, extending to other sphingomyelins and other lipid classes including dihydrosphingomyelins and monohexosylceramides. Complete knockout of its paralog VPS26b promotes an enrichment of BACE1-cleaved APP CTFs (Beta-CTFs) in brain-derived exosomes and may alter exosomal biogenic pathways. Similar trends were seen in a neuronal-specific knockout (via Camk2-Cre recombinase) of retromer’s linchpin, VPS35. Most importantly, an unbiased proteomic screen of CSF collected from mice with a selective knock out of VPS35 in forebrain neurons (engineered using the Camk2 system) uncovered a total of 71 hits (52 parametric and 19 nonparametric) from the 1505 proteins detected. Pathway analysis and follow-up studies identified two distinct molecular categories with previously established relevance to AD: BACE1 substrates and MAPT (more commonly referred to as tau). We report that, both in vivo and in vitro, neuronal-selective knockout of VPS35 causes increased secretion of the N-terminal fragments (NTFs) of BACE1 substrates APLP1 and CHL1 as well as total tau, and importantly, that these events occur independent of cell death. Further, we find evidence of convergence of these pathways in both mouse and human CSF. However, as these BACE1 substrates likely accumulate in plaques, we propose CSF total tau as a biomarker of endosomal dysfunction with utility over the entire course of AD progression. We have identified and validated a series of in vivo biomarkers that are reflective of AD-associated endosomal dysfunction. While clearly sensitive to this cellular pathology, future work is required to determine their specificity. Additionally, follow-up studies are required to show that interventions which rescue endosomal dysfunction affect this molecular profile. The identified biomarkers hold great promise for early detection of endosomal dysfunction in AD and for tracking its course, during the disease progression and for clinical trials. Furthermore, the unexpected but validated finding, showing that increased CSF tau is reflective of AD-associated endosomal dysfunction, suggests that endosomal dysfunction is a universal deficit shared among AD patients in its earliest stages of disease.